Rishiri transportation

Hello! I'm just in the process of finalising the itinerary for an upcoming trip in June and I have a few questions regarding the logistics of transportation on Rishiri island. We're going to catch the first ferry from Wakkanai which arrives at Oshidomari at 0855 and need to be on the last ferry to Rebun (departs Oshidomari at 1305) because we're staying there that night. As we will be travelling with 2 small children strapped to us in carriers we are not interested in hiking to the top of the mountain, hence the half day travel. Our intention is to go to Ponyama and Himenuma but I'm a bit uncertain about the timing of it all. Here's the plan I've come up with:
Arrive 0855, catch taxi from the ferry terminal to the 3rd station campground. Take the walking trail to Ponyama, then follow on to Himenuma. This is where it gets a bit tricky because I've estimated that we'd arrive at Himenuma around 1145-1200 and the bus to the ferry terminal is either 1134 or 1404... one too early, one too late. Walking to the ferry would take about an hour according to Google maps.
Questions:
1) should we be able to easily find the taxi from the ferry?
2) What does the timing of 30-45 minutes for 3rd station to Ponyama take into account?
3) The timing listed for Ponyama to Himenuma is 60-90 minutes. Is that 60 for going down the mountain and 90 for going up? If we can do the walks in 30 and 60 we *should* be able to catch the bus. Or in the least, have more time available to walk to the ferry.
4) Is there a possibility of getting a taxi from Himenuma?
5) Judgements aside please, if we were to catch a taxi would the driver object to taking small children? I know taxis are exempt from the car seat laws and won't have seating.
6) Is there an information booth with hiking maps?

Thank you!

Have you checked the sightseeing tour bus?

http://www.soyabus.co.jp/teikan.htm

"Rishiri A course" departing Oshidomari ferry terminal at 9:10 and arriving at 12:45 will fit your ferry.

It costs 3300 yen for adult and 1900 yen for child.

Reservation is not mandatory, but strongly recommended.

0162-22-3114[AM9:00�`PM5:00]

Thanks frog1954. I hadn't strongly considered the bus tour because it's in Japanese and my husband and our 3yr old wouldn't understand a word of it. Also, we were looking forward to enjoying the hiking trails. Nevertheless I can see the definite positives for the tour. We'll be doing plenty of hiking on Rebun so it's not like we'll miss out on much.

I didn't see any age listed for the child ticket. Is it school age and above?

Is it school age and above?

I also can't find the definition of "child". In general, yes it is primary school age, 6 to 11. Below 6 years old child is free of charge (1 child per 1 acommpanying adult or school age child).

By the way, there are some guide-tour companies in Rishiri and they organize 2-3 hours tours which may fit your plan.

Rishiri Hana Guide Club
http://risiri-hana-guide.info
2 hours, 3800 yen per person.

Rishiri Shima Guide Center
http://www.rishiri-shimaguide.jp
Pon mountain 3 hours, 5000 yen per person.

Rishiri Nature Guide Service
http://www.maruzen.com/tic/guide/
Pon mountain trecking 3 hours, 7560 yen per person.

Those are great, thanks! Now we just need to decide what we'd most like to see and how. I really appreciate your assistance.